White House chief medical adviser Anthony Fauci says there is currently no need for variant-specific COVID-19 booster shots.

Fauci spoke to reporters on Wednesday on the effectiveness of vaccines against the Omicron variant of the coronavirus.

He said the effectiveness of two doses of the Pfizer or Moderna vaccines is "significantly low" against Omicron in preventing infection and serious illness.

But he also said preliminary study findings show that a third dose of the vaccine led to a substantial degree of elevation of neutralizing antibodies.

Fauci urged people to get their third jabs, saying, "Our booster vaccine regimens work against Omicron."